Epilayers of highly C-doped material were grown by means of low-pressure metalorganic vapor phase epitaxy and were studied by using high-resolution X-ray diffraction. An X-ray diffraction simulation program which was based upon the dynamic theory was developed so that the C self-compensation effect, and passivation due to interstitially incorporated H in the C-doped material, could be taken into account. It was noted that, whereas the (004) Bragg reflection could be used to measure only the lattice contraction that was caused by C doping, the (002) Bragg reflection was highly sensitive to C occupation of the Ga or As sub-lattice. The fitting of simulated diffraction curves, of both the (004) and the (002) reflections, to the experimental ones permitted the evaluation of the interstitially incorporated H concentration. It therefore permitted the calculation of the total C concentration and the net hole concentration. This technique was successfully applied to various C-doped samples, and the results were confirmed by Hall measurements and secondary-ion mass spectrometry.

Q.Liu, A.Brennemann, H.Hardtdegen, A.Lindner, W.Prost, F.J.Tegude: Journal of Applied Physics, 1996, 79[2], 710-6